<span style="font-family: arial, helvetica, sans-serif; font-size: 15px; ">I read a post by someone saying they &ldquo;used a Octura flex coupler to a solid shaft&rdquo;.</span><br style="font-family: arial, helvetica, sans-serif; font-size: 15px; " /><br style="font-family: arial, helvetica, sans-serif; font-size: 15px; " /><span style="font-family: arial, helvetica, sans-serif; font-size: 15px; ">Has anyone else done this?</span><span style="font-family: arial, helvetica, sans-serif; font-size: 15px; ">Did you have any problems arise when you did it? Was your engine mounted solid or did you use rubber mounts? Which way would be better as I can see pros &amp; cons either way.</span><br style="font-family: arial, helvetica, sans-serif; font-size: 15px; " /><br style="font-family: arial, helvetica, sans-serif; font-size: 15px; " /><span style="font-family: arial, helvetica, sans-serif; font-size: 15px; ">I have a couple of vintage rc boats with solid shafts but unable to find u-joints with a 1/4-28 thread to a 3/16 solid shaft to upgrade engines. I thought about connecting straight to the solid shaft with a flex coupler but was not sure it was a good idea.</span><br style="font-family: arial, helvetica, sans-serif; font-size: 15px; " /><br style="font-family: arial, helvetica, sans-serif; font-size: 15px; " /><span style="font-family: arial, helvetica, sans-serif; font-size: 15px; ">Most of the u-joints I found are for electric motors and do not list the thread size. Who has a 1/4-28 (for .21 Rossi &amp; .61 Webra crankshaft thread sizes) u-joint for a 3/16 solid shaft?</span>